Industry now generally recognizes the benefits of structured preventive maintenance programs under which the performance of production machinery and tooling is continuously or periodically monitored. Such monitoring has many aspects, however, one substantially developed surveillance field is concerned with the vibrational aspects of rotational machinery. An evaluation of the performance state of a machine may be carried out utilizing industrial vibration analyzers in conjunction with a transducer such as an accelerometer, a velocity or displacement pick-up. These devices provide outputs representing those units of measurement which are treated by sophisticated filtering, averaging, integrating, digitization and the like, to develop numerical values for analysis in terms of amplitudes, time, and frequency domains and the like.
Experienced technicians, using dedicated analytical software, employ such numerical data to evaluate trends and rather accurately predict optimum maintenance intervals, as well as break-downs. These technicians also utilize portable analyzing systems for carrying out such analysis at the situs of a machine undergoing investigation.
The collection of vibrational data as part of a structured preventive maintenance program varies with the production criticality of the machinery and tooling involved. Highly critical devices may be under continuous surveillance. In this regard, the transducers employed at the commencement of the data collection scheme are securely fastened to the machines, for example, utilizing threaded studs and the like. The data collected from such fixed installations is typically transmitted by permanent transmission cables to a monitoring station for compilation and analysis. Less critical data may be acquired using hand-held vibration meters. Over the recent past, an intermediate data collection approach involving a portable, microprocessor-driven data collector has achieved popularity, a highly successful, pioneering data collector, for example, being described in U.S. Pat. No. 4,612,620, by Davis, et al., entitled "Apparatus for Collecting Scheduled Maintenance Data", issued Sep. 16, 1986, and assigned in common herewith. In general, the data collectors perform in connection with a scheduling facility such as a personal computer having software designed to download a predetermined data collection route into the portable device. The user of the device then actuates any of a number of keys at a keyboard on the hand-held device, and moves from position to position along a displayed "route" of data collection, placing a transducer coupled via transmission cable to the data collector upon each measurement position. Those measurement positions are detailed in terms of units of measurement, orientation of the probe, and the like, at a readout on the collector. The user then actuates a collection program generally by depressing a push-button and the data is collected from the transducer, whereupon it is subjected to certain signal treatment such as filtering, integration and is then digitized and placed in memory. At the end of a data collection period, the user then reconnects the data collector with the scheduling facility and uploads collected data for analysis at that facility.
As is the case with any form of data collection, the data collected is only as good as the quality of its derivation at the beginning of the process. This point of derivation is the connection between the transducer and the machine under surveillance. The most preferred and most accurate collection approach is one wherein the transducer is physically connected to the machine being evaluated. Typically, as noted above, this is carried out utilizing a threaded stud. Where that secure connection between transducer and machine cannot practically be achieved, then collection turns to approaches wherein less accurate but still valuable data are developed. For example, where no "hard" connection can be made between the transducer and a machine, a strong permanent magnet may be attached to the transducer to hold it against the machine. Such an approach to coupling generally results in a loss, for example, of high frequency vibration data. A less desirable next but practical approach to data collection is by hand-holding a transducer assembly against the machine during the interval of data collection. Such an approach often is used where the point to be measured on the machine is essentially otherwise inaccessible or may represent a region wherein hand-positioning a transducer would impose a safety hazard. For such data collection, the industry has resorted to the utilization of probe devices which are attached to the transducers. The combined transducer and probe assembly then is hand-held against the machine measurement position. As before, this approach to measurement results in, for example, high frequency fall-off. To aid in the physical collection of data using a probe coupled transducer, it also is desirable to provide for actuation of the entry or store function in the data collector utilizing the hand which is holding the probe. Where such an arrangement is provided, then the user may hold the portable device in one hand, observing numerical values for the data being collected, while actuating the store button and holding the transducer probe assembly in position against the machine monitoring point with the other hand.
For any vibration data collection employing data collector devices, portable analyzers and the like, it is highly desirable that the user have the ability to optimize transducer utilization. Accordingly, where a transducer can be threadably attached to the measurement point, then that most accurate form of data collection should be utilized. Alternately, where the transducer alone utilizing a strong magnet may be employed in the absence of some "hard" connection, then that next desired approach should be utilized. Finally, for points of measurement where the former two approaches are inefficient or unavailable to the user, then the probe approach may be made employed without undue additional procedure. As is apparent, a convenience of flexibility in configuring a transducer based pick-up for the above delineated modes of attachment would be quite advantageous.